The Last Stand, By Nathaniel Philbrick

Every year in late June, Custer's Last Stand is reenacted on the high plains of Montana. When Custer led out the 7th Cavalry in 2003 - the year I witnessed it - the audience stood and cheered with turbo-charged patriotism. The men they were saluting were not the re-enactors they could see, of course, but the loved ones in Iraq they couldn't. Custer was then, and remains, the zeitgeist on horseback, the closest thing to America made flesh, in all its triumphant glory, and its shameful double-dealing.

For Nathaniel Philbrick - writing on "Custer, Sitting Bull and the Battle of the Little Bighorn" in the dog-days of the second Bush's second administration - his Custer, like the country he served, is "unabashed in his greed". Nor will any reader be left in doubt on Philbrick's attitude toward America's latter-day imperialism, which he presents as an extension of the westward expansion that cost Custer and countless others their lives.

But this does not mean he is prepared to boo and hiss Custer either. On the contrary: he acknowledges that, despite the flaws, "there was something about Custer that distinguished him from other human beings". Why else the book? To sum him up, Philbrick borrows a phrase Herman Melville used to characterise Captain Ahab: "All mortal greatness is but disease". The name of the disease we never learn; only its symptoms.

Among them may be numbered an above-average interest in Shakespeare's Julius Caesar, which Custer saw no less than 40 times when visiting New York. Since his best friend, Lawrence Barrett, was playing Cassius, Philbrick speculates that Custer must have cast himself as Brutus. In which case, Brutus becomes a prophet when he says: "I shall have glory by this losing day".

Back in Montana, as the simulated conflict progressed, and Sitting Bull, Crazy Horse, Gall et al moved in for the kill, a cloud of dust occluded the battleground, as if to demonstrate what "the fog of war" really meant. It was a reminder that all eyewitness accounts of the massacre are doubly suspect; subject both to poor visibility, and the notorious unreliability of memory. Philbrick quotes a veteran of the 7th Cavalry (Custer divided his troop before the Last Stand, accidentally sparing many lives), who had begun to suspect that he had only been at the Little Bighorn in a dream.

In his attempt to make sense of that nightmare, Philbrick seems to have read every available source. His conclusion is that there really was no Last Stand, that Custer was killed not in defensive mode, but while still invading hostile territory. That Philbrick has, nevertheless, chosen to call his book The Last Stand is surely an acknowledgement that - when it comes to Custer - history has become legend. Sitting Bull and the Sioux nation (not to mention the Cheyenne) lost that day too, for the victory marked the beginning of their end.

Although the events described take place many miles from the sea, the Pequod and the Bounty are never far away (hardly surprising, given that Philbrick's previous books have had nautical themes). Not only did Custer have to subdue the Sioux, he also (like Captain Bligh) had to pacify his own subordinates; in particular ever-pickled Reno, and ever-resentful Benteen, who is quoted thus: "There are many excellent ways of finding out the disposition and nature of a man. I know of no better way than having to live on shipboard with one for a number of years... Next, in default of salt-water facilities ... campaign with a man in the cavalry ... Thus I became acquainted with General Custer."

To tell the truth, the Custer we get to know is not so far removed from the glory-hunter portrayed in George MacDonald Fraser's Flashman and the Redskins. Without old Flashy rogering is at a minimum, though Philbrick does not fail to address Custer's wandering eye, and his alleged affair with the sultry Cheyenne captive Monahsetah (to which he allows some credence).

But what gives Philbrick's book its greatest distinction is neither its CSI style research, nor its nautical subtext, but the willingness of its author to move beyond the evidence-based procedure of the conventional historian. "It is also my firm belief," he writes, "that the spiritual and visionary aspects of experience are essential to understanding not only Sitting Bull but also Custer and his wife".

Thus the cause of Custer's ultimate humiliation might not be hubris after all, but the bad karma created by the desecration of Sioux burial sites a few nights before the battle. Likewise, it seems that the Sioux achieved only a pyrrhic victory because they ignored Sitting Bull's injunction (vouchsafed in a vision) not to loot or mutilate their dead enemies. These quasi-religious flourishes nudge the book towards the bloody meridian that separates the quotidian from the world of Cormac McCarthy, but Philbrick's anger is colder, and his linguistic register considerably less apocalyptic. All, you feel, is not yet lost.

Clive Sinclair's 'True Tales of the Wild West' is published by Picador